Why do mosquitoes bite some people more than others?

- asks Allison from Austin

Credit: [Oxbow Park Naturalization Project].
By | Posted September 10, 2007
Posted in: Ever Wondered?, Featured, Life Science
Tags: , , , ,

Every summer, they come. They sneak through the windows and ravage your ankles; they find the one spot on your left shoulder that didn’t get drenched in a layer of DEET (God bless you, Deep Woods Off!) and gnaw, chomp, and suck away.

From May to September, many of us – covered in scars and bloody scabs, the remnants of these bites now gone bad – live side-by-side with people who, despite living in the same house and even sleeping in the same bed, are seemingly less vulnerable to the vicious six-legged predators. It turns out, a mosquito’s snacking preference for one person over another is not just a curious annoyance, it’s also a medical concern: Since malaria and other diseases are transmitted by bites, people who get bitten a lot are more likely to become ill. Because of this, researchers are working to find the mechanisms in mosquitoes that cause them to sniff out you, and not your neighbor.

Scientists have identified several proteins found in mosquitoes’ antennae and heads that latch on to chemical markers, or odorants, emitted from our skin. These markers are produced by the natural processes of our bodies and, like neon signs, they let the mosquitoes’ smell center know you’re around (though the process that then guides them to you is not well understood). Flies and mosquitoes share a number of the same genes that dictate production of these odorant-binding proteins, which have specific sites that will catch or bind with certain chemicals in the air. Some scientists suggest that certain characteristics attract mosquitoes, thereby leading us to have more bites than others. Some of the top candidates: the amount of carbon dioxide in the breath, pregnancy, body temperature, alcohol and odorant markers based on blood type.

Blood-type markers are chemicals released by people of a specific blood type – so if someone with AB blood emitted a marker, it would be different than that released by B. One study found persons with Type O blood suffered more mosquito landings because of the odorant markers they emit than any other blood type, making their juices a hot commodity for blood banks, as well as Asian Tiger Mosquitoes, which carry West Nile Virus. Not only were Type O’s more likely to be landed on, but the study found that for any blood type, people who secreted a chemical marker about their blood type through their skin (both blood type and secretor status are determined by genes) were bitten much more than non-secretors; 24 percent in the case of the Type O’s. Other researchers estimate about 15 percent of the population, based on their genes, don’t emit chemical markers of their blood type through their skin and saliva, so something else has to be calling the mosquitoes to them.

Pregnancy seems to be a big winner for mosquito attraction, probably because mothers-to-be exhale 21 percent more carbon dioxide (quite a turn-on to the six-legged species) and are on average 1.26 degrees Fahrenheit warmer around the belly than their non-pregnant counterparts, due to the temperature of amniotic fluid. Also, having just 12 ounces of beer increases your mosquito appeal, possibly because of the increase in body temperature it causes or because skin markers change when metabolizing cocktails – unfortunate since outdoor drinking is a highlight of summer anywhere.

One researcher suggested smell is unimportant, and what really matters to the mosquito currently chomping on your toe is not the smells you’re giving off, rather it’s finishing her meal without being swatted away. Because of this, she’s better off attacking “less defensive” animals, rather than more defensive, and so is evolutionarily predisposed to biting lazy or incapacitated prey (reference drinking above).

Infectious disease experts are anxious to solve the mosquito preference puzzle so they can design repellants tailored to vulnerable people, which would either block an individual’s smell signatures or disarm a mosquito’s scent receptors. Unfortunately, a specific answer to your skin-piercing question continues to itch away at scientists, and I suggest stocking up on bug repellant in the meantime.

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  1. we are sooooooooooooo vulnerable when the mosquitos and flys and other insects arive in the summer months…….I am 69 and suffer every summer….I am ABpositive blood type…..Help me … does anyone have an answer of cure????

    Guadalupe Camacho, July 22, 2014 at 10:55 pm
  2. I am AB positive…………every year I suffer with mosquito bites….anyone out there.. has a cure???? I am the only one that gets bit in a crowd. Lupe. :(

    Guadalupe Camacho, July 22, 2014 at 10:58 pm
  3. I’ve always wondered why I never get bitten by mosquitoes, even when everyone around me is getting chomped away. I knew there had to be some kind of scientific based reasoning and I theorized it had to do with smells, so this is a very interesting read.

    amber, July 28, 2014 at 2:08 am
  4. I do beive everything on here because im the only one wth o- blood n the house and the only one that gets bit and they get bigger than the peoples with out o blood ..

    kara, July 30, 2014 at 10:57 am
  5. The blood type thing cant be right because I used to get bit all my childhood terribly. After I had my first child 29 years ago, I haven’t gotten a single mosquito bite. I figured it had to do with my chemistry changing after pregnancy. I just watched one land on me and move to 6 different spots trying to get a good spot. It never broke skin. I was just going to keep watching til it flew away, which is what they usually do, but my husband asked me to swat it to protect him….they love him.

    mary, August 3, 2014 at 11:04 am
  6. Straight up couldn’t be bothered to read the article because your opening pictures is a Mayfly, not a mosquito.
    You may want to address that issue. It’ll lend an air of research, knowledge and professionalism to your work.

    John, August 8, 2014 at 4:07 pm
  7. I can be in a crowd, say at a picnic and i will get eaten alive while others suffer no bites. This happens all the time, so much so that i am hestiant to engage in outside activities and repellants have no affect. Still haven’t a clue how to protect myself. These bites hurt and they ruin your skins!!! I need a defense!

    Msknoitall, August 14, 2014 at 8:36 am
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  10. #11 is an idiot. Here are facts SCIENTIFIC FACTS RESEARCHED and just because it doesn’t happen TO HER she says she’s, “…not buying the blood theory.” What a moron. So if it does not happen to you that’s the way of the world. pfffft. Why is the world full these stupid people?

    The Vanilla Godzilla, October 25, 2014 at 10:24 am
  11. Whaaaaaaaaaatt? I’m Blood Type A and I usually keeps on getting bitten by mosquitoes more than that of my sister who’s Blood Type O. It’s so frustrating especially during the cold season that mosquitoes are hiding inside the houses and dark places. I’m always the poor one in my family. I have to put ointments everywhere in my body :/

    Chess Risette, December 5, 2014 at 8:52 am
  12. Well, my blood type is B+ positive and get bitten more than others. I often see mosquitoes hovering around me more. It’s messy to use the creams and my main remedy is with a mosquito net that is pretty simple and more practical to me. And yes the ones that attach me inside the net sometimes, face the wrath of my chinese mosquito bat!!

    Vijayan Aravamudhan, December 13, 2014 at 10:22 am
  13. This is not a picture of a mosquito.

    Ryan, December 23, 2014 at 11:27 pm
  14. It really is just coincidence rather than blood type It is possible that it was just where you were standing at that moment of popularity of the mosquitos at that time chemicals in blood are tremendous to I get bit even in las Vegas by mosquitoes they itch really bad . Blood type has nothing to do with this. I get bit Simi alot body temputure average of 97.2F my blood type I think is AB+ Positive.

    Darius Tabassi, January 8, 2015 at 11:48 pm
  15. I have just read the article, but not all the comments.
    My wife was a rare blood type and had terrible trouble
    with Mosquitoes until she was diagnosed with Leukaemia
    they never went near her again. Can they detect
    if the blood is not right?

    Gerry Olohan, March 23, 2015 at 9:52 am
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  17. I am with O+ve. I am a victim of mosquito.

    Redwan, May 18, 2015 at 10:55 am
  18. I have B- blood and no one gets bit when I’m around cause all the Mosquitos are chewing on me.

    Debra, June 1, 2015 at 7:48 am
  19. Blood type has nothing to do with bite ratio. My wife and I are both O+ she doesnt get bitten I do. Body temp also out. Both reading same temp, difference between us besides different sexes is I have an extremely high fast moving immune system due to pollen reaction. Being +/-or A,AB,O seems little in bite ratio from reading all the articles seem little to no effect. Maybe we are all looking into this far to much. It is what it is. Chemical inbalance within each of us. Blood impurities she gives blood 4 times a year and it is accepted, I do not give blood as test results came back as not being clean enough to use. No I do not have aids or anything harmful to me it is just not clean enough. Look at the countries reports come in from hygiene not always great and temps are high thrieving areas for insects to increase in. Oh the bloke from the army, hydration theory is out I drink 1 pint water a day my wife 4 pints water a day I still get bitten. You all want possible solution for going out without getting bitten, simple move to north pole insects dont like extreme cold

    Rich, June 18, 2015 at 1:23 pm
  20. I’m not buying the blood type causing more bites. My DH is Type O- and never gets a bite. I am A+ and get bit on a regular basis. Neither one of us smoke or drink.
    I will say that I noticed something interesting this summer though. I have been using different soaps. My normal soap was Irish Spring. Of course I always got bit. I changed to a citrus soap, and I didn’t get bit. I ran out of my citrus on vacation and used a coconut soap, and I got bit again. I also tried an Almond soap and got bit. I finally went back to the citrus, and I don’t get bit. I can’t tell you everthing that attracts mosquitoes, but I can definitely tell you what can help prevent them from sucking your blood….citrus soap. Hope it works for others as well!

    Stephanie, June 19, 2015 at 4:01 am
  21. I’m type B+ and it seems every day about 2-3 more bites get added to my collection. While other folks say they haven’t seen a mosquito since moving to southern California, I’m a native that’s walking proof that they’re around.. I always say the bugs want happy blood so they go for be positive blood heh

    Amber, July 9, 2015 at 10:03 am
  22. I believe in the temperature points. But u know tastes of meats are not always the same-some are sweeter-even same fruits can differ in taste. When go to buy items or even fishes,chickens…at point and kill you make a choice-select the one that attracts you. So mosquito goes to the sweeter person. Bees do go to flowers that produce more juices to aid formation of honey-all animals have a level of intelligence

    Ekeh kelechi Emmanuel, July 19, 2015 at 3:20 pm
  23. Ever since I can remember I’ve had serious reactions to bee stings and mosquitoes. After I had my second child my reaction to the bites we’re not as bad, but I still get eaten alive.

    Kat, July 29, 2015 at 10:55 am
  24. why do mosquitos bite us

    drexel, August 8, 2015 at 8:29 am
  25. my answer to this post is>>>>>>>First of all, it’s not in your head. Mosquitoes really do prefer some people to others, says Dr. Jonathan Day, a medical entomologist and mosquito expert at the University of Florida. And that time your grandmother told you your skin was just sweeter? There’s some truth to that, Day says. “Some people produce more of certain chemicals in their skin,” he explains. “And a few of those chemicals, like lactic acid, attract mosquitoes.” There’s also evidence that one blood type (O) attracts mosquitoes more than others (A or B).

    Unfortunately, your genes dictate your blood type and the chemical makeup of your birthday suit. Genetics also determine several other factors that could make you an object of blood-sucking affection for your local mosquito population, Day says. Maybe the most important: Your metabolic rate, or the amount of carbon dioxide (CO2) your body releases as it burns energy.

    Mosquitoes use CO2 as their primary means of identifying bite targets, Day says. Why? “All vertebrates produce carbon dioxide, so what better way could there be for a mosquito to cue in on a host?” And while it’s true that you can moderate your metabolic rate through diet and exercise, you can only change your metabolism so much, Day says.

    “Pregnant women and overweight or obese people tend to have higher resting metabolic rates, which may make them more attractive to mosquitoes,” he explains. Also, drinking alcohol or physically exerting yourself raises your metabolic rate—and also your appeal to winged biters, he adds. (Exercising before grabbing a beer and heading outside = asking for trouble.)

    While CO2 detection is the primary technique mosquitoes and other blood-sucking bugs use to spot hosts, they also rely on secondary cues to differentiate you from cars, decaying trees, and other CO2-producing objects. And you can control some of those secondary cues, Day says.

    For example: Dark clothing is more attractive to mosquitoes than light oufits. Why? “Mosquitoes have problems flying in even a slight wind, and so they keep close to the ground,” Day explains. Down there, they spot hosts by comparing your silhouette to the horizon. Dark colors stand out, while light shades blend in, he says. At the same time, lots of motion distinguishes you from your surroundings. So if you’re moving around a lot or gesturing, you might as well be shouting, “Hey, mosquitoes! I’m right here, ladies!” (Only the females bite, Day says.)

    drexel, August 8, 2015 at 8:35 am
  26. I think it probably has to do with a person’s body PH rather than their blood type. The PH of your blood would actually change the way you taste to the mosquitoes, fleas, etc. I’ve noticed that on the rare occasion I’m bitten by a mosquito, it doesn’t swell up as much if I eat healthy, but as soon as I start eating a bunch of sweets- BIG ITCHY MESS!

    Veronica, September 1, 2015 at 3:03 pm
  27. Hi I’ve never bin bitten and I honestly think it’s because I’m vodka drinker I no that sounds bad lol but I really believe it’s true x

    Melissa webb, September 10, 2015 at 6:00 pm
  28. I’m always the one getting bitten. I am trying home remedies. So far, nothing is working.

    Carol, September 24, 2015 at 9:28 pm
  29. I worry about using deet products on a daily basis so I am trying to prepare something safe to apply to my ankles. I will post here if successful. Here is what I plan to try: rubbing alcohol applied to ankles, vinegar applied to ankles. Also wondering if I should buy a dog’s flea collar and wear it on my ankle. Has anyone tried this and is it safe?

    Carol, September 24, 2015 at 9:31 pm
  30. I am B negative.

    Carol, September 24, 2015 at 9:32 pm
  31. This may be disturbing because I thing those six legged are smart they can sense which person is sick or more sick then the other n that’s who they attack! The weak!

    Liset, November 2, 2015 at 3:27 am
  32. I am 57,white male type O+. Not trying to be different. But I can go into swamps or other areas infested with ticks, fleas and mosquitoes and not have a bite of any kind. As a experiment I placed a tick on my arm and repeatedly it moved to get off of me without attempting to bite. I do not understand why this is but I readily except it. Just wonder if I am not alone in this. ?

    Cal, November 28, 2015 at 9:03 pm
  33. I’m O+ and I donate blood, so I don’t think its part of blood type. I get bitten like crazy. I also am overweight, yet I exercise 1 hour daily, or at least 3x a week. It doesn’t matter if I use repellents, I’ve watch what I eat, I can run a mile, they just love me. I think its hormonal.

    curly-01, February 29, 2016 at 2:18 pm
  34. My son is 11 and has never been bitten. His twin sister gets eaten alive. We have always wondered why.

    Rubygal, March 17, 2016 at 4:06 pm
  35. Reading all your posts, being a lifelong victim of mosquitos and being an RN, the article and the comments lead me to believe it is probably based on hormones (women stated that the biting changed after the birth of a child when women’s hormones go through a big change). There does not seem to be blood type specific based on all your comments. It could be the theory of the secretor theory! Since 15% of us are not secretors that could explain the low percent of us that say they do not get sucked on. I am an O negative secretor and am a life time victim of mosquitos.

    Gordon Waite, April 8, 2016 at 1:31 am
  36. I don’t normally get bitten, always thought it was to do with the fact that the odour my body gives off when I sleep smells more like a dead, rotting animal than a live one. I binge drink and smoke which causes a stench when my body is cleaning my system after a binge.

    Dan, May 10, 2016 at 12:40 pm
  37. I am O negative . I never ger mosquito bites. They don’t like me and if they land on me they don’t stay long if I get bit I don’t get a bump. However I’ve seen ticks jump twards me. If I go hiking I never leave the trail and come home with them on my neck. They like that spot l. They were also

    Julie Durfee, May 15, 2016 at 11:27 pm
  38. I completely agree with this excellent article. My blood type is O+ n i am only one who is getting bitten by the mosquitoes in crowd.I was actually shocked by reading the article.Damn useful one.

    padma, June 7, 2016 at 2:48 am
  39. I am a 52 year old white male.My blood type is O+.I very rarely get bitten and have been like this as long as i can remember.Even if i do get bitten i am never left with a mark or a feeling of itchyness.I have put on a huge amount of weight in the last few years,wear dark clothing and still do not get bitten.I used to drink but don’t drink now and that also has made no difference.I am the same with fleas that normally leave me alone but if i do get bitten,i am never left with any mark of the bite..My wife and daughter on the other hand suffer immensely and will scratch and scab up.I thought they were weird.It seems i am the strange one.

    Richy Norman, June 20, 2016 at 12:52 pm
  40. I’m not quite sure what blood type I have, but while hanging outside with friends, I always have more than everyone. One of my friends said it was because of my blood sugar levels…is this true? I don’t know my blood sugar levels, but is this a possibility?

    Alicia M., June 29, 2016 at 11:33 am
  41. I’m 61, caucasian female, type O+ blood and have been a mosquito feast all my life. They itch immediately and I will scratch and tear them apart til they’re infected! But, that all stopped this year when I discovered two things. 1. If I do get bitten, I immediately wet the area put bentonite clay on it and mist again, then let it dry for awhile. No itch afterward. 2. If I chew a big clove of organic garlic (approx. 15 min. before going out) and hold it in my mouth swishing it for as long as I can stand before swallowing it, they leave me alone……but, so does everyone else!

    Terry, October 20, 2016 at 6:48 pm
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